The present invention relates to a pressure-type pouring furnace, and more particularly to an art to be applied to a casting line consisting of a series of mold frames, each mold frame having a plurality of pouring gates.
Conventional pressure-type pouring furnaces are disclosed, e.g., in Japanese Patent Unexamined Publication No. Hei. 2-25269 and Japanese Utility Model Unexamined Publications Nos. Sho. 62-10952 and Sho. 62-50860. Each of these furnaces includes a molten metal chamber containing molten metal within the furnace body, a receiving siphon and a pouring siphon communicating with each other at the bottom of the molten metal chamber, a furnace cover sealably covering the top of the molten metal chamber, and a pressuring unit connected to the furnace cover. Some of these furnaces further include pouring nozzle on a pouring chamber on top of the pouring siphon, with a single pouring nozzle being shown on the pouring chamber. Further, a pressure-type pouring furnace using a stopper on the pouring nozzle is disclosed in Japanese Utility Model Examined Publication No. Sho. 63-7422. However, in the case of producing small castings such as taps, a mold frame is often designed to include two or more molds, each mold having its own pouring gate. Thus, various techniques have been devised to pour the molten metal from the single pouring nozzle of the pressure-type pouring furnace to the casting line consisting of a series of mold frames having a plurality of pouring gates.
FIG. 3 is a time chart for FIG. 4 which shows an operation plan of a conventional example 1; FIG. 4 is a plan view showing the operation plan of the conventional example 1; FIG. 5 is a plan view showing an operation plan of a conventional example 2; and FIG. 6 is a plan view showing an operation plan of a conventional example 3. In FIGS. 3 through 6, reference characters x.sub.w, x.sub.p designate a pitch at which the mold frames are arranged and a pitch at which the pouring gates within a single mold frame are arranged, both pitches not only satisfying a relationship x.sub.z =x.sub.w -x.sub.p, but also indicating a direction of movement of the casting line with "y" indicating a direction of movement orthogonal thereto. Reference characters t.sub.1, t.sub.2 designate moved positions at different timings on the same casting line with the respective symbols indicating a pouring gate not pouring, .smallcircle.; having poured, ; and during pouring, .circleincircle.. In FIGS. 3 and 4, the line repeats its movements x.sub.p , x.sub.z for time intervals W.sub.p, W.sub.z, and the molten metal is poured to a pouring gate A and a pouring gate B for time intervals P.sub.a, P.sub.b when the line is stopped. Examples of time interval are as shown in FIG. 3, and a single cycle lasts 31 seconds as shown in FIG. 3. In FIG. 5, which shows the conventional example 2, an auxiliary conveyor making the movement x.sub.p is located immediately below the pouring nozzle, while main conveyors, each making the movement x.sub.w, are located ahead and behind the auxiliary conveyor. In FIG. 6, showing the conventional example 3, auxiliary conveyors making the movements x.sub.p and x.sub.z are located immediately below the pouring nozzle, and a main conveyor making the movement x.sub.w runs in parallel thereto. Time charts for the plans shown in FIGS. 5 and 6 will not be shown.
The above conventional art allows the single pouring nozzle of the pressure-type pouring furnace to pour the molten metal into the casting line consisting of a series of mold frames having a plurality of pouring gates. However, since the mold frame arrangement pitch rarely coincides with a value exactly twice the pitch of the pouring gates of a single mold frame, the line must repeat differently distanced movements x.sub.p, x.sub.z, for different time intervals W.sub.p, W.sub.z, or the main and auxiliary conveyors must be employed, etc., which, as a result, makes the casting line forwarding mechanism complicated. In addition, the casting process is long with its pouring operation performed one by one by the pouring gates A, B. On the other hand, an attempt to move a pressure-type pouring furnace with a casting line of simple design is problematic in practically achieving the frequent movement of the pouring furnace with the molten metal contained therein.